Handwritten Prescriptions and Look-alike Drug Names

Double, double, toil and trouble! William Shakespeare wasn't talking about drug names when he wrote this line in his play, Macbeth, but he sure had the right idea! Today, many medicines have names that look very similar to the names of other medicines. So mix-ups are possible when a pharmacist fills your prescription, especially if it's a handwritten prescription, as the following example shows.

While reading a drug information leaflet about a new prescription medicine, a young man discovered he had received the wrong medicine from the pharmacy. His doctor had given him a handwritten prescription for Lamictal (lamotrigine) 100 mg to treat bipolar disorder, an illness that affects thoughts, feelings, and behavior. (Lamictal can also be used to help control seizures.) The pharmacist misread the handwritten prescription as "levothyroxine 100 mcg," a thyroid medicine. Fortunately, the young man discovered the error before taking the wrong medicine. He returned the levothyroxine to the pharmacy and received the correct drug, lamotrigine.

Handwritten prescriptions are a common factor leading to mix-ups between medicines with look-alike names. For example, when levothyroxine and lamotrigine are typewritten, the drug names appear to be very different. But when handwritten, the names can look remarkably alike, especially if using cursive letters, because both drug names:

Start with the letter "l"

Have "ot" as the fourth and fifth letters of the name

Include a letter (y or g) that forms the same type of loop below the line in the middle of the name

End with the letters "ine."

Mix-ups between medicines with lookalike names happen because of "confirmation bias." That is, people tend to see what they expect to see, such as the name of familiar medicine. For example, have you ever bought a can or carton of Pepsi when you intended to buy Diet Pepsi? If you have, you've experienced confirmation bias.

Doctors who include the reason you are taking the medicine on the prescription can help pharmacists avoid these kinds of mistakes. Most medicines with look-alike names are not used to treat the same condition. So, having your doctor list the reason for the medicine alerts the pharmacist to your condition and serves as a check to make sure the correct medicine is provided. But if a mix-up happens, reading the drug information leaflet that comes with your medicine can help you notice the error right away.

With the large number of drugs on the market today, the potential for medicines to have a name that looks or sounds like another medicine is high. For this reason, most drug companies test the brand names they plan to use for new medicines. They contract with companies that get working nurses, pharmacists, and doctors to look at handwritten prescriptions of the medicine to see if it looks like another medicine. This process leads to fewer medicines with look-alike names. Still, there are a lot of medicines on the market with similar names.

See the table below for examples. Electronic prescriptions that doctors enter into a computer produce legible prescriptions that are less likely to be misread. But only 10% of doctors send prescriptions to pharmacies using a computer.

You can also help prevent errors:

Make sure the pharmacist knows the reason you are taking a medicine

Inspect the medicine before you leave the pharmacy to be sure it looks as expected if you are refilling a prescription

Talk to a pharmacist about the medicine when picking up a new prescription